Annealing apparatus



Aug. 25, 1942.

J. R. wlRT rs1-AL v2,293,873

ANNEALING APPARATUS Filed May 22, 1941 3 Sheets-Sheet l 1%VENTQR 5M 4^. m .2l/WAPA ATTORNEY@ Aug. 25, 1942. J. R. wlRT ETAL I ANNEALING APPARATUS Filed May 22, 1941 3 Sheets-Sheet 2 Aug. 25, 1942. J. R. wlRr :r1-AL 2,293,873

ANNEALING APPARATUS Filed May 22, 1941 3 Sheets-Sheet 5 J- 'N ENI R-s al( M $444,

' ATTORNEYA Patented Aug. 25, 1942 ANNEALIN G APPARATUS John B. Wirt and William A.

Ind., assignors to General Fletcher, Anderson, Motors Corporation,

Detroit, Mich., a corporation of Delaware Application May 22, 1941, Serial No. 394,684

2 Claims.

This invention relates to apparatus for annealing continuously moving lengths of rods, tubing wire and the like. More particularly the invention relates to an apparatus for annealing welded steel tubing made in a continuous mill comprising forming rolls, a seam Welder, an annealer and other apparatus for surface ilnishing of the tube.

An object of the present invention is to provide an improved annealing apparatus which provides for heating the tube electrically while in an annealing chamber containing an inert or reducing atmosphere. More particularly it is an object of the invention to provide for making good electrical contact with different portions of the tubing by means which distributes the pressure along a substantial portion of the tube, so that the pressure applied to the tubing at any particular point is not s great as to cause it to be distorted while in a relatively soft condition. This is accomplished by the use of the electrode boxes forming parts of the annealing chamber and containing quantities of metal .pel-

lets mixed with graphite powder.

In this connection it is a further object to provide for rotatably supported the boxes on an axis coinciding with the axis of the moving tubf" ing so that the boxes may be inverted and the metal pellets and graphite may gr'avitate to other parts of the boxes and thus clear the space through which the tubing passes so that the tubing may be threaded through the annealing apparatus without interference by the metal pellets and graphite.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings wherein a preferred embodiment of the present invention is clearly shown.

In the drawings:

Figs. 1 and 2 taken together comprise a front elevation of a welding apparatus involving the present invention;

Fig. 3 is an end view taken in the direction of the arrow 3 of Fig. 1.

Figs. 4 and 5 are sectional views taken respec tively on the lines 4 4 and 5 5' of Fig. 1.

Fig. 6 is a fragmentary longitudinal sectional view of a portion of the annealer at the end of Fig. 2;-and y Fig. 7 is a sectional. view on the line of Fig. 6.

The annealing apparatus comprises a channel iron bed 20 supported by pedestals 2l and 22. 55 a fixed bar At each end thereof, the bed 20 supports brackets 23 and 24 provided with trunnion rollers 25 for supporting tubular shafts 26 and 21 which are fixed between clamp 28 attached by screws 29 to brackets 30 welded to a channel frame 3|.

Frame 3| supports seven electrode boxes 32 made of cast bronze arranged as shown in Figs. 1 and 2. There are groups of two boxes each located near each end of the frame 3| and a group of three boxes midway between the end groups. Ihe end groups are electrically connected together by bus bars 33 attached by screws 34 to the bottoms of the end boxes 32 and spaced therefrom and fromeach other by copper plates 35. The bars 33 are insulatingly supported by the middle group of boxes 32. The boxes 32 of the center group are insulated from the boxes 32 of the end groups. Non-conducting plates 36 are located between each of the center groups of boxes and the bus bars 33. The screws 31 which secure bars 33 and plates 36 to the boxes 32 are insulated from the bars 33. Ihe end Vgroups of boxes 32 are grounded upon the frame 3| which is electrically connected with the pedestals 2| and 22. Between the frame 3| and each of the boxes 32 of the end group, there is located a metal spacing block 38 (Fig. 4). Screw 33 secures the end boxes 32 and the middle plate 38 to the frame 3|. The boxes 32 of the center group are insulated from the frame 3| by nonconducting spacers 40 (Fig. 5). Screws 4| which secure the boxes of the center group and the insulating plates 40 to the trame 3| are insulated from the frame 3|. The center group of boxes 32 are connected together by bus bar 42 provided with a plurality of wire connecting terminals I3 all connected with one -pole of an alternating current source, the other pole being connected in a similar manner to the bus bars 33. When the end boxes are charged positive- 1y the center boxes will be charged negatively and vice versa during the A. C. cycle. Therefore, current ilows either from the end boxes toward the center or in the reverse manner. Since the end boxes are grounded, there is no external circulating current.

Referring to Fig. 6, the right end box 32 pro- .vides a back Wall 50 integral with top Wall 5|,

bottom wall 52 and side walls 53. The front opening is partly enclosed by cover plate 54 attached by screws 55 (Figs. 1 and 2) which extends a little over half way down from the top wall 5| (Fig. 4). The remainder of the front opening is closed by a removable plate 56 and 51 carrying pairs of spaced ears il.

each -palr supporting a pin 59 pivotally supporting a clamping lever til. Referring to Fig. 4, each lever l! -is secured in clamping position by engaging the eccentric portion 5I of the levei` 62 pivoted at 63 on an arm St pivoted at Eton a bracket 66 attached by screws tl to the fixed plate 55. By moving the lever 'B2 down or clockwisein Fig. l the lever Bll is firmly wedged into position and holds the plate tt in position upon the box 32. When the lever 535i is moved up *Hardly or counter-clockwise and the is lilsewise moved upwardly the lever is released so that the plate may be removed.

:lille plate is attached. at each end by screws to blocks ll. Each block li is wider than the thickness oi the side walls 53 and is provided with grooves l la each of which receives an end portion 53a or" the side wall 53. Bloch 'li is provided with a semi-circular notch. l matching with a semi=circular notch 'it provided in side wall c fi mnrounded semi-annular bosses ld. The .nce between flat surfaces ci the two bosses on the .nside and outside of the box wall 53 equal to .the thickness of the block il. The wall 53 and the block il are shaped to receive a tube or heat resisting and electrically nonconducting material l5. It has been found that a tube ci Alsimag is satisfactory for this purpose. The Alsimag tubes are purchased in short lengths so that any section of the tube may be replaced without necessitating replacing the whole line of .'fllsimag tubing. Between adjacent boxes t2 of each group, one length of tubing it isA sufcient; andthe tube sections between the adjacent boxes enclosed in a metal protecting band i6. The u mg T to he t ated (Fig. 6) moves from right toward left. Therefore, the entrance end of each actory section is beveled. as indicated at short renactorgv section l5 connects end it with a shalt 2t or ill, the shaft coprite for purpose. The enter= ing end of sh t 2l' is beveled at 2in also to facilitate threading o the tubing through the annealing Each end group of boxes is connected with the other end group of boxes by aline o refractory sections l5 providing a refractory pipe connecting the nearest adjacent boxes of an end o andV another group. "ihese refractory secii are enclosed in a .tubular case corna tubular half shell of steel and tubular half shell tl of copper or other non-magnetic material (Fig. 5). These two haii shells extend nearly the full distance between the nearest ad jacent boxes of the center and end groups; but they do not contact any of the boxes so that no electrical connection is made between them. These half shell members t@ and 8l are clamped between pairs of clamping bars 82 and 83. Bar is secured to frame el. Bar 8d is provided with spaced ears t4 pivoted at 85 upon bar 32. Bar 82 carries a pin 85 providing a pivot for a pair or spaced arms @l carrying a pin. 83 providing a pivot for a lever having an'eccentric 9G adapted to clampingly engage the lower end of each bar d3. By pushing the handle down. the bar 33 is caused to grip .the half shell al and to force it the haii shell tti and thereby secure the two half shells iirmly in position. When the handle is raised the eccentric is moved away from the bar a distance sufcient to permit the arm ill to drop below the end of the bar 83 so that the bar 83 may be swung upwardly l nl a.,

till

about its pivot thereby releasing the half shell 75 member ti so that it can be removed to provide access to the refractory lining units 15".

The metallic case comprising the metallic half shell members t@ and tl encloses the refractory lining unit 'l5'. is inductively related to the tubing T which conducts alternating current. In order to reduce the electrical and magnetic efects upon the members il@ and tl caused by the alternating current passing through the tubing T, the members t@ and Si provide electrical gaps at their abutting edges which minimize eddy currents in duced in. these members. The fact that one of these members is non-magnetizable helps to minimize magnetic effect. The reason that the section is made of steel rather than copper is to increase the resistance to the iow of eddy currents.

Each box 32 houses a quantity of metal pellets itt, preferably of copper mixed with powdered graphite. Practically all of the length of tubing between the side walls of each box is under the pressure of the copper pellets itil. This dis tributed pressure is sufficient to transfer electric current between the pellets and tubing without requiring the pressure at any point to be so great as to distort the tubing T although it should heated to such high tempertaure that its walls would be relatively soft.

While the tubing is passing through the annealf ing chamber comprising the shafts 26 and 2l, the refractory units 15, l5' and 15" and electrode boxes 32, air is excluded by forcing an inert or reducing gas into the boxes and under sufficient pressure to keep the air from entering the anneal= ing chamber. Each box is connected by a cou pling |05 of electrically non-conducting material and a exible pipe H06 with a gas manifold.

In order to facilitate threading the tubing through the apparatus before the electric current is turned on, the frame 3l and. all parts supported thereby are inverted in order that the metal pellets and the graphite may descend upon the walls 5i of the boxes 32. This is accomplished by turning handwh'eel ,l l@ connected with a shaft IH journalled in a bracket lli? attached by screws l I3 .to the trunnion frame l lil.4 .Shaft lll is provided with a worm meshing with a worm wheel i l5 welded to a shaft 2l. By rotating the shaft 2l at the right end (Figs. 2 and 6) the frame 3l and parts supported thereby and the shaft it at the left end. (Fig. l) are rotated about the axis of the tubing T so that conducting' pellets ltll and the graphite with which they are coated fall upon the normally upper walls 5l of the boxes 322. The graphite reduces abrasion o tubing by .the pellets itil and assists in making good electrical contact with the minimum spariraing.

While the embodiment of the present invention as herein disclosed, constitutesa preferred form, it is to be understood that other` forms might be adopted, all coming within the scope of the claims which follow.

What is claimed. is as follows:

l. Apparatus for annealing tubing comprising an elongated frame, a plurality of spaced metallic electrode boxes having their back walls attached to the frame and having their side walls provided with openings located closer to their bottom' walls than to their top walls, the bottom wall being the lowermost wall in the normal position of the box, the front walls of the boxes being provided with openings to provide access to the openings of the sides to facilitate threading the tubing through the side openings, covers for the openings detachably secured to the boxes, tubular sections having tubular, refractory, electrically nonconducting lining bodies connected with the boxes at their side openings so as to provide aligned guides for the passage of a length of tubing to be annealed and for the passage of a nonoxidizing gas around the tubing, quantities of electrically conducting pellets located in the boxes for making electrical connections between the boxes and the tubing, the aggregate volume of each quantity of pellets being such that the pellets submerge the tubing to a substantial depth when the boxes are in normal position, the size of the pellets being in excess of the clearance between the tubing and the refractory bodies, means for supporting the frame for rotation about the axis of the tubular sections, means for rotating the frame in order to cause the pellets to slide down the back walls of the boxes into pockets provided by the front, back, side and top walls of the boxes, the pockets being of such dimensions as to receive the pellets so that they are below the side-openings of the boxes, thereby permitting removal of the front wall covers to provide access to the side openings for tube threading purposes without spilling the pellets, means for electrically connecting the boxes with a current source, and means for conducting a non-oxidizing gas under pressure into the boxes, said gas passing through the interstices between the pellets and through the side openings in the boxes and into the tubular sections.

2. Apparatus according to claim l in which the tubular sections are secured in position by pairs of clamping members, one member of each pair being ilxed to the frame and the other member of each pair being supported by the fixed member of each pair, some of the pairs of clamping members directly contacting refractory lining bodies and comprising xed members which are provided by the side walls of the boxes and removable members which are carried by the removable covers of the boxes.

JOHN R. WIRT. WILLIAM A. FLETCHER. 

